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| | ==Crystal Structure of D-galactose-6-phosphate isomerase in a substrate-free form== | | ==Crystal Structure of D-galactose-6-phosphate isomerase in a substrate-free form== |
| - | <StructureSection load='4lfk' size='340' side='right' caption='[[4lfk]], [[Resolution|resolution]] 1.96Å' scene=''> | + | <StructureSection load='4lfk' size='340' side='right'caption='[[4lfk]], [[Resolution|resolution]] 1.96Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[4lfk]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Lacrl Lacrl]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4LFK OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4LFK FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[4lfk]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Lacticaseibacillus_rhamnosus_Lc_705 Lacticaseibacillus rhamnosus Lc 705]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4LFK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4LFK FirstGlance]. <br> |
| - | </td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4lfl|4lfl]], [[4lfm|4lfm]], [[4lfn|4lfn]]</td></tr> | + | </td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4lfk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4lfk OCA], [https://pdbe.org/4lfk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4lfk RCSB], [https://www.ebi.ac.uk/pdbsum/4lfk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4lfk ProSAT]</span></td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">lacA, LC705_00641 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=568704 LACRL]), lacB, LC705_00640 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=568704 LACRL])</td></tr>
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| - | <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Galactose-6-phosphate_isomerase Galactose-6-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.26 5.3.1.26] </span></td></tr>
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| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4lfk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4lfk OCA], [http://pdbe.org/4lfk PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4lfk RCSB], [http://www.ebi.ac.uk/pdbsum/4lfk PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4lfk ProSAT]</span></td></tr> | + | |
| | </table> | | </table> |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Galactose-6-phosphate isomerase]] | + | [[Category: Lacticaseibacillus rhamnosus Lc 705]] |
| - | [[Category: Lacrl]] | + | [[Category: Large Structures]] |
| - | [[Category: Jung, W S]] | + | [[Category: Jung WS]] |
| - | [[Category: Pan, C H]] | + | [[Category: Pan CH]] |
| - | [[Category: Isomerase]]
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| - | [[Category: Isomerization]]
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| - | [[Category: Rossmann fold]]
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| - | [[Category: Rossmann-like alpha-beta-alpha sandwich fold]]
| + | |
| - | [[Category: Sugar-phosphate binding]]
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| Structural highlights
Publication Abstract from PubMed
D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like alphabetaalpha sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique alpha7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Calpha of the alpha6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.
Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.,Jung WS, Singh RK, Lee JK, Pan CH PLoS One. 2013 Aug 28;8(8):e72902. doi: 10.1371/journal.pone.0072902. PMID:24015281[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Jung WS, Singh RK, Lee JK, Pan CH. Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates. PLoS One. 2013 Aug 28;8(8):e72902. doi: 10.1371/journal.pone.0072902. PMID:24015281 doi:http://dx.doi.org/10.1371/journal.pone.0072902
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